Descriptive Approaches

Most broadly, the literature frequently describes "polydrug use" or "poly-substance use." This nondiagnostic designation generally describes the use of multiple substances rather than framing the use and its effects in clinical terms, which is the intent of diagnosis. As such, polydrug use describes, at minimum, the use of multiple substances, whether licit or illicit. In the treatment research literature, "polydrug use" is often used to describe the lifetime number of drugs regularly used to a threshold SUD, in addition to the index substance (Ball, Carroll, Babor, & Rounsaville, 1995; Feingold, Ball, Kranzler, & Rounsaville, 1996). However, in other than addiction or mental health treatment settings, the expressions "polysubstance use" or "polysubstance abuse" are frequently meant to describe the use by subjects of as few as two substances, such as cocaine and alcohol, alcohol and cannabis, or opiates and cocaine (Ross, Kohler, Grimley, & Bellis, 2003). In a more differentiated conceptualization, the use of multiple substances that cause impairment is frequently described as "polydrug abuse."

In an effort to further distinguish patterns of use, Grant and Hartford (1990) framed "polydrug use" either as simultaneous, which is the use of multiple drugs at the same occasion, or concurrent, which is the use of different substances on different occasions. Use of different substances is common in patients with alcohol dependence or substance dependence (Caetano & Weisner, 1995), the majority of whom use substances simultaneously (Staines, Magura, Foote, Deluca, &Kosanke, 2001). Longitudinal studies in community samples are able to discriminate between simultaneous and concurrent polydrug use, but a differential impact upon subsequent health outcomes including psychological distress, physical symptoms, and services utilization has not been identified (Earleywine & Newcomb, 1997).